The requirement to remove abandoned cables is all over the place in the NEC

372.13 Discontinued Outlets.When an outlet is abandoned, discontinued, or removed, the sections of circuit conductors supplying the outlet shall be removed from the raceway. No splices or reinsulated conductors, such as would be the case of abandoned outlets on loop wiring, shall be allowed in raceways.(374.7 & 390.7 have the same language)

640.3 Locations and Other Articles.Circuits and equipment shall comply with 640.3(A) through (L), as applicable. (A) Spread of Fire or Products of Combustion. The accessible portion of abandoned audio distribution cables shall not be permitted to remain. See 300.21.

You are not required to tear up the building to remove abandoned cables but if you can get them out (read:"accessible") you are supposed to.If you tag them "spare", "reserved for future use" or words to that effect they can stay.That is a loophole you can drive Michael Moore's butt through

Tel/data cables abandoned above the ceiling is a very common situation. I am sure the next guy to run wiring would be very happy if the code were strictly complied with in this case.

A different situation:We have a floor of a building that is mostly open but was finished with drywall (walls and ceiling). There are several ceiling light outlets and switches (on columns that were finished with drywall). The circuits go to load centers that agian were recessed in drywall. The space will be built out with some partitions and drop lay-in ceilings. I want to remove the light fixtures and switches, cover the boxes and disconnect the load centers. All new wiring will be run above the new lay-in ceilings with a new panelboard.Basically the existing electric will be disconnected and abandoned.

The intent of all of the 2002 changes in reference to abandoned cables basically say remove all you can. If that means cutting them off where they enter the wall that is what I would do. Certainly anything above a T bar ceiling should go if you don't have a reasonable expectation that they could be reused. Even then I would roll them up and stash them near the wall they come out of to clear the way for the next guy. I came here from the computer business and one of the most frustrating problems we had was abandoned cables under the floor.